1. Field of the Invention
The present invention relates to organic copper compounds for making copper (Cu) thin-films used in wiring of semiconductor devices by a metal organic chemical vapor deposition (hereinafter referred to as MOCVD) process, to liquid mixtures (solutions) containing the compounds, and to copper thin-films prepared by the MOCVD process using the solutions.
2. Description of the Related Art
As an organic copper compound used in a MOCVD process, copper complex Cu(I) tmvs.multidot.hfac (wherein tmvs represents trimethylvinylsilane and hfac represents hexafluoroacetylacetonate), which satisfies a combination of strict chemical, structural, and electrical requirements over a relatively wide range, has selective deposition ability, and is liquid at room temperature, is well known in Japanese Unexamined Patent Application Publication No. 5-202,476. This compound, however, is extremely unstable, and is readily decomposed at room temperature to precipitate metallic copper and to form copper(II)(hfac).sub.2 as a by-product. Thus, the organic copper compound cannot be uniformly supplied during a film deposition process, resulting in less reproducible film deposition.
In order to solve this problem, copper(I) atms.multidot.hfac (wherein atms represents allyltrimethylsilane), which exhibits a more stable vaporization rate than that of copper(I) tmvs.multidot.hfac, high volatility, and high thermal stability, and is liquid at room temperature, is disclosed in Japanese Unexamined Patent Application Publication Nos. 7-252266 and 10-131514.
On the other hand, a copper precursor compound is disclosed in Japanese Unexamined Patent Application Publication No. 10-195654. This compound contains copper(I) hfac and methoxymethylsilylolefin ligand. When the compound is heated to a vaporization temperature, the electron donor ability of oxygen in the methoxymethylsilylolefin ligand provides a stable bond between the copper and the methoxymethylsilylolefin ligand. In this copper precursor compound, the oxygen atom of the methoxy group primarily suppresses the volatility of the copper precursor compound. Thus, the copper precursor compound exhibits improved thernal stability and a prolonged life.
Both copper(I) atms.multidot.hfac disclosed in Japanese Unexamined Patent Application Publication Nos. 7-252266 and 10-135154 and the copper precursor compound disclosed in Japanese Unexamined Patent Application Publication No. 195654, as well as copper(I) tmvs.multidot.hfac, exhibit low film deposition rate and poor adhesiveness to underlayers compared to physical deposition processes, such as a sputtering process.